/**



* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.



* Author: Drew Diller



* Email: drew.diller@gmail.com



* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/



* Version: 0.0.7a



* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license



*



* Example usage:



* DD_belatedPNG.fix('.png_bg'); // argument is a CSS selector



* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement



**/







/*



PLEASE READ:



Absolutely everything in this script is SILLY.  I know this.  IE's rendering of certain pixels doesn't make sense, so neither does this code!



*/







var DD_belatedPNG = {







	ns: 'DD_belatedPNG',



	imgSize: {},



	



	createVmlNameSpace: function() { /* enable VML */



		if (document.namespaces && !document.namespaces[this.ns]) {



		  document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');



		}



		if (window.attachEvent) {



			window.attachEvent('onbeforeunload', function() {



				DD_belatedPNG = null;



			});



		}



	},



	



	createVmlStyleSheet: function() { /* style VML, enable behaviors */



		/*



			Just in case lots of other developers have added



			lots of other stylesheets using document.createStyleSheet



			and hit the 31-limit mark, let's not use that method!



			further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx



		*/



		var style = document.createElement('style');



		document.documentElement.firstChild.insertBefore(style, document.documentElement.firstChild.firstChild);



		var styleSheet = style.styleSheet;



		styleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');



		styleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');



		styleSheet.addRule('img.' + this.ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */



		this.styleSheet = styleSheet;



	},



	



	readPropertyChange: function() {



		var el = event.srcElement;



		if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {



			DD_belatedPNG.applyVML(el);



		}



		if (event.propertyName == 'style.display') {



			var display = (el.currentStyle.display == 'none') ? 'none' : 'block';



			for (var v in el.vml) {



				el.vml[v].shape.style.display = display;



			}



		}



		if (event.propertyName.search('filter') != -1) {



			DD_belatedPNG.vmlOpacity(el);



		}



	},



	



	vmlOpacity: function(el) {



		if (el.currentStyle.filter.search('lpha') != -1) {



			var trans = el.currentStyle.filter;



			trans = parseInt(trans.substring(trans.lastIndexOf('=')+1, trans.lastIndexOf(')')), 10)/100;



			el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */



			el.vml.image.fill.opacity = trans; /* complete guesswork */



		}



	},



	



	handlePseudoHover: function(el) {



		setTimeout(function() { /* wouldn't work as intended without setTimeout */



			DD_belatedPNG.applyVML(el);



		}, 1);



	},



	



	/**



	* This is the method to use in a document.



	* @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'



	**/



	fix: function(selector) {



		var selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */



		for (var i=0; i<selectors.length; i++) {



			this.styleSheet.addRule(selectors[i], 'behavior:expression(DD_belatedPNG.fixPng(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */



		}



	},



	



	applyVML: function(el) {



		el.runtimeStyle.cssText = '';



		this.vmlFill(el);



		this.vmlOffsets(el);



		this.vmlOpacity(el);



		if (el.isImg) {



			this.copyImageBorders(el);



		}



	},



	



	attachHandlers: function(el) {



		var self = this;



		var handlers = {resize: 'vmlOffsets', move: 'vmlOffsets'};



		if (el.nodeName == 'A') {



			var moreForAs = {mouseleave: 'handlePseudoHover', mouseenter: 'handlePseudoHover', focus: 'handlePseudoHover', blur: 'handlePseudoHover'};



			for (var a in moreForAs) {



				handlers[a] = moreForAs[a];



			}



		}



		for (var h in handlers) {



			el.attachEvent('on' + h, function() {



				self[handlers[h]](el);



			});



		}



		el.attachEvent('onpropertychange', this.readPropertyChange);



	},



	



	giveLayout: function(el) {



		el.style.zoom = 1;



		if (el.currentStyle.position == 'static') {



			el.style.position = 'relative';



		}



	},



	



	copyImageBorders: function(el) {



		var styles = {'borderStyle':true, 'borderWidth':true, 'borderColor':true};



		for (var s in styles) {



			el.vml.color.shape.style[s] = el.currentStyle[s];



		}



	},



	



	vmlFill: function(el) {



		if (!el.currentStyle) {



			return;



		} else {



			var elStyle = el.currentStyle;



		}



		for (var v in el.vml) {



			el.vml[v].shape.style.zIndex = elStyle.zIndex;



		}



		el.runtimeStyle.backgroundColor = '';



		el.runtimeStyle.backgroundImage = '';



		var noColor = (elStyle.backgroundColor == 'transparent');



		var noImg = true;



		if (elStyle.backgroundImage != 'none' || el.isImg) {



			if (!el.isImg) {



				el.vmlBg = elStyle.backgroundImage;



				el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")')-5);



			}



			else {



				el.vmlBg = el.src;



			}



			var lib = this;



			if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */



				var img = document.createElement('img');



				lib.imgSize[el.vmlBg] = img;



				img.className = lib.ns + '_sizeFinder';



				img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */



				img.attachEvent('onload', function() {



					this.width = this.offsetWidth; /* weird cache-busting requirement! */



					this.height = this.offsetHeight;



					lib.vmlOffsets(el);



				});



				img.src = el.vmlBg;



				img.removeAttribute('width');



				img.removeAttribute('height');



				document.body.insertBefore(img, document.body.firstChild);



			}



			el.vml.image.fill.src = el.vmlBg;



			noImg = false;



		}



		el.vml.image.fill.on = !noImg;



		el.vml.image.fill.color = 'none';



		el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;



		el.runtimeStyle.backgroundImage = 'none';



		el.runtimeStyle.backgroundColor = 'transparent';



	},



	



	/* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */



	vmlOffsets: function(el) {



		var thisStyle = el.currentStyle;



		var size = {'W':el.clientWidth+1, 'H':el.clientHeight+1, 'w':this.imgSize[el.vmlBg].width, 'h':this.imgSize[el.vmlBg].height, 'L':el.offsetLeft, 'T':el.offsetTop, 'bLW':el.clientLeft, 'bTW':el.clientTop};



		var fudge = (size.L + size.bLW == 1) ? 1 : 0;



		



		/* vml shape, left, top, width, height, origin */



		var makeVisible = function(vml, l, t, w, h, o) {



			vml.coordsize = w+','+h;



			vml.coordorigin = o+','+o;



			vml.path = 'm0,0l'+w+',0l'+w+','+h+'l0,'+h+' xe';



			vml.style.width = w + 'px';



			vml.style.height = h + 'px';



			vml.style.left = l + 'px';



			vml.style.top = t + 'px';



		};



		makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);



		makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1);



		



		var bg = {'X':0, 'Y':0};



		var figurePercentage = function(axis, position) {



			var fraction = true;



			switch(position) {



				case 'left':



				case 'top':



					bg[axis] = 0;



					break;



				case 'center':



					bg[axis] = .5;



					break;



				case 'right':



				case 'bottom':



					bg[axis] = 1;



					break;



				default:



					if (position.search('%') != -1) {



						bg[axis] = parseInt(position)*.01;



					}



					else {



						fraction = false;



					}



			}



			var horz = (axis == 'X');



			bg[axis] = Math.ceil(fraction ? ( (size[horz?'W': 'H'] * bg[axis]) - (size[horz?'w': 'h'] * bg[axis]) ) : parseInt(position));



			if (bg[axis] == 0) {



				bg[axis]++;



			}



		};



		for (var b in bg) {



			figurePercentage(b, thisStyle['backgroundPosition'+b]);



		}



		



		el.vml.image.fill.position = (bg.X/size.W) + ',' + (bg.Y/size.H);



		



		var bgR = thisStyle.backgroundRepeat;



		var dC = {'T':1, 'R':size.W+fudge, 'B':size.H, 'L':1+fudge}; /* these are defaults for repeat of any kind */



		var altC = { 'X': {'b1': 'L', 'b2': 'R', 'd': 'W'}, 'Y': {'b1': 'T', 'b2': 'B', 'd': 'H'} };



		if (bgR != 'repeat') {



			var c = {'T':(bg.Y), 'R':(bg.X+size.w), 'B':(bg.Y+size.h), 'L':(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */



			if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */



				var v = bgR.split('repeat-')[1].toUpperCase();



				c[altC[v].b1] = 1;



				c[altC[v].b2] = size[altC[v].d];



			}



			if (c.B > size.H) {



				c.B = size.H;



			}



			el.vml.image.shape.style.clip = 'rect('+c.T+'px '+(c.R+fudge)+'px '+c.B+'px '+(c.L+fudge)+'px)';



		}



		else {



			el.vml.image.shape.style.clip = 'rect('+dC.T+'px '+dC.R+'px '+dC.B+'px '+dC.L+'px)';



		}



	},



	



	fixPng: function(el) {



		el.style.behavior = 'none';



		if (el.nodeName == 'BODY' || el.nodeName == 'TD' || el.nodeName == 'TR') { /* elements not supported yet */



			return;



		}



		el.isImg = false;



		if (el.nodeName == 'IMG') {



			if(el.src.toLowerCase().search(/\.png$/) != -1) {



				el.isImg = true;



				el.style.visibility = 'hidden';



			}



			else {



				return;



			}



		}



		else if (el.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {



			return;



		}



		var lib = DD_belatedPNG;



		el.vml = {color: {}, image: {}};



		var els = {shape: {}, fill: {}};



		for (var r in el.vml) {



			for (var e in els) {



				var nodeStr = lib.ns + ':' + e;



				el.vml[r][e] = document.createElement(nodeStr);



			}



			el.vml[r].shape.stroked = false;



			el.vml[r].shape.appendChild(el.vml[r].fill);



			el.parentNode.insertBefore(el.vml[r].shape, el);



		}



		el.vml.image.shape.fillcolor = 'none'; /* Don't show blank white shapeangle when waiting for image to load. */



		el.vml.image.fill.type = 'tile'; /* Ze magic!! Makes image show up. */



		el.vml.color.fill.on = false; /* Actually going to apply vml element's style.backgroundColor, so hide the whiteness. */



		



		lib.attachHandlers(el);



		



		lib.giveLayout(el);



		lib.giveLayout(el.offsetParent);



		



		/* set up element */



		lib.applyVML(el);



	}



	



};



try {



	document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */



} catch(r) {}



DD_belatedPNG.createVmlNameSpace();



DD_belatedPNG.createVmlStyleSheet();







/* EXAMPLE */







/* string argument can be any CSS selector */



/* .png_bg example is unnecessary */



/* change it to what suits you! */